StickyKeysBrowserTest (in interactive_ui_tests) fail with SingleProcessMash. By looking into its details, I've found two issues which cause the failures:

the test fixture creates EventGenerator with the browser window (https://cs.chromium.org/chromium/src/chrome/browser/chromeos/accessibility/sticky_keys_browsertest.cc?q=sticky_keys&sq=package:chromium&g=0&l=41), which generates events directly to the browser. Since sticky-keys are handled in the shell, we need to use EventInjector; either creating EventGenerator with nullptr or using UIControls will do this.

ws::EventInjector (and InjectedEventHandler) injects event by calling OnEventFromSource() of an EventSink, which calls aura::WindowEventDispatcher directly (https://cs.chromium.org/chromium/src/services/ws/injected_event_handler.cc?sq=package:chromium&g=0&l=41), and this actually bypasses EventRewriters in the WindowTreeHost. This means sticky keys are not properly tested here because it is implemented as an EventRewriter.


Maybe we should change EventInjector to call EventRewriters.